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From Al Chou <>
Subject Re: [math] Users Abilities vs. Developers was RE: [math] Very legitimate reasons to draw up Presicison Unit Tests.
Date Tue, 27 May 2003 17:45:07 GMT
--- Phil Steitz <> wrote:
> Hope, Matthew wrote:
> >>-----Original Message-----
> >>From: Phil Steitz [] 
> >>Sent: 27 May 2003 02:01
> >>To: Jakarta Commons Developers List
> >>Subject: Re: [math] Very legitimate reasons to draw up 
> >>Presicison Unit Tests.
> > 
> > <snip>
> > 
> >>* Support multiple algorithms when appropriate and let the 
> >>users decide.
> >>   For example, we will likely want to add an alternative to Cholesky
> >>   decomposition and allow the user to choose.
> > 
> > <snip>
> > 
> > I think there is a question here form the users point of view. How much
> > mathematical and numerical knowledge should be assumed.
> Not much, I hope. We will not have met the goals outlined in the 
> proposal if users *need* to know very much math to be able to use the 
> tools effectively.
> > It is reasonable to my mind to assume that a user of this libraray should
> be
> > aware of performance considerations with regards to which algortihm is used
> > (since in any case if it's important to them they should be testing it!)
> But
> > understanding of the intricacies of numerical programming strikes me as
> > something that would be best hidden away unless the user *really* wants to
> > play.
> I agree.  The key thing is to "let" the user decide without "forcing" 
> the user to decide.  Reasonable default behavior should be easy to get. 
>   Hopefully, we have not (yet) violated that in what has actually been 
> implemented up to now.  We need to keep looking at this.
> > 
> > I did a Maths and Comp degree and found the [math] threads wonderfully
> > refreshing after so long programming business code but realistically would
> > expect most users to just want to get a reasonable answer without worrying
> > about whether the values they were passing in reuired one or the other
> > algorithms...
> I agree, but this is a little bit tricky in some cases.

Amen to that.  The success of a numerical algorithm is sometimes determined by
what problem it is asked to solve (e.g., some matrix problems are
ill-conditioned because of the specific values in the matrix), which is why
problem solving often requires forethought.  I support trying to make tools
easy to use, but that can often be very difficult and sometimes impossible. 
Still, we should strive for it, all the while remembering that we're not in the
AI business here, and sometimes the user will really have to provide
information they might not have known a priori they would need to know.


Albert Davidson Chou

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